Self-Changing Gears
Encyclopedia
Self-Changing Gears was a British company, set up and owned equally by Walter Gordon Wilson
and John Davenport Siddeley to develop and exploit the Wilson or pre-selector gearbox. Self-Changing Gears designed, built and licensed transmissions for various applications including light and heavy road vehicles, military, marine, and rail vehicles as well as motor racing cars.
The original company Improved Gears Ltd was incorporated on 28 December 1928, and this later became Self-Changing Gears. The company moved a number of times in the early years, and in 1938 settled in premises at Lythalls Lane, Coventry
. During the war, additional premises were used at Burbage, Leicestershire
.
In 1935, J D Siddeley sold his interests in Armstrong-Siddeley motors (including Self-Changing Gears) to Hawker Aircraft
forming Hawker-Siddeley
. In 1951 Leyland Motors Ltd
bought into the company, resulting in each party owning one-third of the company, and in 1957 Leyland bought-out Hawker-Siddeley's shares in the company, thereby gaining control.
s and shunting locomotives
had gearboxes made by Self Changing Gears. Examples include British Rail Class 100
and British Rail Class 04
and some of these are still in use on heritage railways.
The name Self-Changing Gears is sometimes confusing: the gearboxes are not fully automatic, selection of gear ratio remains a manual choice, but the gear-changing and any clutch control needed is automated. The gearboxes were used in conjunction with a fluid coupling
so no clutch
pedal was needed.
From about 1935 to 1960, buses by the AEC, Daimler, and sometimes Leyland and Guy companies offered Preselector gearboxes, either as an option or as standard. London buses invariably used this transmission, along with other cities. Country area buses still commonly retained manual transmissions as they did not have the requirement of constant stopping and starting at bus stops. The London specification included compressed air operation of the change-gear pedal, where others used unassisted operation.
Around 1960 the bus industry was changing from traditional vehicles with engine at the front and driver in a small separate cabin alongside, to entrance at the front alongside the driver, and the engine and gearbox remotely mounted under the floor or at the rear. SCG Ltd devised the Semi Automatic gearbox, under their brand name "Pneumocyclic" as an advance, it had the same gearbox principle but instead of pre-selecting a gear and then separately operating a change gear pedal, both functions were combined and operated from a small lever alongside the steering wheel, the driver just moved this to the next gear and the transmssion responded. The mechanism was operated either by air pressure or low-voltage electrics, although the physical gearshifting in the gearbox was nearly always by air pressure, (some vehicles used high pressure hydraulics, notably BMMO vehicles). This style of transmission was also widespread in UK buses, from a range of manufacturers, until different types came onto the market in the 1980s. A further advance was the Fully Automatic gearbox, which still used the same principles but shifted gears automatically. This was pioneered on the well-known London "Routemaster" type, and later spread, although not widely, to other vehicle types.
Walter Gordon Wilson
Major Walter Gordon Wilson was an engineer and member of the British Royal Naval Air Service. He was credited by the 1919 Royal Commission on Awards to Inventors as the co-inventor of the tank, along with Sir William Tritton....
and John Davenport Siddeley to develop and exploit the Wilson or pre-selector gearbox. Self-Changing Gears designed, built and licensed transmissions for various applications including light and heavy road vehicles, military, marine, and rail vehicles as well as motor racing cars.
Ownership changes
Following the death of Walter Wilson in 1957, his son A.Gordon Wilson took over the running of the company until his retirement in 1965.The original company Improved Gears Ltd was incorporated on 28 December 1928, and this later became Self-Changing Gears. The company moved a number of times in the early years, and in 1938 settled in premises at Lythalls Lane, Coventry
Coventry
Coventry is a city and metropolitan borough in the county of West Midlands in England. Coventry is the 9th largest city in England and the 11th largest in the United Kingdom. It is also the second largest city in the English Midlands, after Birmingham, with a population of 300,848, although...
. During the war, additional premises were used at Burbage, Leicestershire
Burbage, Leicestershire
Burbage is a civil parish in Leicestershire, England. It is a southern suburb of the town of Hinckley. According to the United Kingdom Census 2001 the parish had a population of 14,324.-History:...
.
In 1935, J D Siddeley sold his interests in Armstrong-Siddeley motors (including Self-Changing Gears) to Hawker Aircraft
Hawker Aircraft
Hawker Aircraft Limited was a British aircraft manufacturer responsible for some of the most famous products in British aviation history.-History:...
forming Hawker-Siddeley
Hawker-Siddeley
Hawker Siddeley was a group of British manufacturing companies engaged in aircraft production. Hawker Siddeley combined the legacies of several British aircraft manufacturers, emerging through a series of mergers and acquisitions as one of only two such major British companies in the 1960s. In...
. In 1951 Leyland Motors Ltd
Leyland Motors Ltd
Leyland Motors Limited was a British vehicle manufacturer of lorries, buses and trolleybuses. It gave its name to the British Leyland Motor Corporation formed when it merged with British Motor Holdings, later to become British Leyland after being nationalised...
bought into the company, resulting in each party owning one-third of the company, and in 1957 Leyland bought-out Hawker-Siddeley's shares in the company, thereby gaining control.
Railway applications
Many of British Railways' first generation diesel multiple unitDiesel multiple unit
A diesel multiple unit or DMU is a multiple unit train consisting of multiple carriages powered by one or more on-board diesel engines. They may also be referred to as a railcar or railmotor, depending on country.-Design:...
s and shunting locomotives
Switcher
A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...
had gearboxes made by Self Changing Gears. Examples include British Rail Class 100
British Rail Class 100
The British Rail Class 100 diesel multiple units were built by Gloucester Railway Carriage and Wagon Company Limited from 1956 to 1958, designed and built in collaboration with the Transport Sales Dept. of T.I. Ltd.-Introduction:...
and British Rail Class 04
British Rail Class 04
The British Rail Class 04 0-6-0 diesel-mechanical shunting locomotive class was built between 1952 and 1962 and was the basis for the later Class 03 built in the British Railways workshops. The Class 04 locomotives were supplied by the Drewry Car Co., which at the time had no manufacturing...
and some of these are still in use on heritage railways.
The name Self-Changing Gears is sometimes confusing: the gearboxes are not fully automatic, selection of gear ratio remains a manual choice, but the gear-changing and any clutch control needed is automated. The gearboxes were used in conjunction with a fluid coupling
Fluid coupling
A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch...
so no clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
pedal was needed.
Bus applications
The bus manufacturing industry was a major customer of the company. Buses on city work need to start and stop every minute or less, and the effort required with a manual gearbox was substantial. In addition, for most of the period when these transmissions were dominant buses still had unassisted steering, and the overall effort needed without assistance was fatiguing.From about 1935 to 1960, buses by the AEC, Daimler, and sometimes Leyland and Guy companies offered Preselector gearboxes, either as an option or as standard. London buses invariably used this transmission, along with other cities. Country area buses still commonly retained manual transmissions as they did not have the requirement of constant stopping and starting at bus stops. The London specification included compressed air operation of the change-gear pedal, where others used unassisted operation.
Around 1960 the bus industry was changing from traditional vehicles with engine at the front and driver in a small separate cabin alongside, to entrance at the front alongside the driver, and the engine and gearbox remotely mounted under the floor or at the rear. SCG Ltd devised the Semi Automatic gearbox, under their brand name "Pneumocyclic" as an advance, it had the same gearbox principle but instead of pre-selecting a gear and then separately operating a change gear pedal, both functions were combined and operated from a small lever alongside the steering wheel, the driver just moved this to the next gear and the transmssion responded. The mechanism was operated either by air pressure or low-voltage electrics, although the physical gearshifting in the gearbox was nearly always by air pressure, (some vehicles used high pressure hydraulics, notably BMMO vehicles). This style of transmission was also widespread in UK buses, from a range of manufacturers, until different types came onto the market in the 1980s. A further advance was the Fully Automatic gearbox, which still used the same principles but shifted gears automatically. This was pioneered on the well-known London "Routemaster" type, and later spread, although not widely, to other vehicle types.